Modern transmitter systems, such as television and radar systems, require generation and phase control of high power signals. In order to obtain sufficient power, multiple high-power signal sources are often combined by the use of hybrid combiners. Those skilled in the art know that hybrid combiners may also be used to split applied signals, and are not limited to combining.
In a radar context, the signals applied to a transmitting antenna must be steered, which requires phase control of the signals applied to each element of the antenna array. In some radar systems, the signals must be applied or “switched” to separate antenna arrays facing in different directions for transmission of electromagnetic signals in the selected directions. In the context of high-power signals such as radar pulses, the switching may be conveniently accomplished by control of the phase of signals applied to the various input ports of a hybrid combiner. Proper switching of signal by the use of a hybrid combiner requires that the phase relationship of the applied signals be closely controlled, as otherwise signals may “leak” away from the desired port to other, non-selected ports.
In the context of a radar system in which the transmission frequencies change from time to time, the frequency changes may result in undesired phase conditions at the hybrid ports, especially at the edges of a frequency band or range. These undesired phase conditions, in turn, may result in leakage of the signal away from the desired ports at some frequencies within a frequency band.
Improved or alternative phase control arrangements and/or methods are desired.